Chem. J. Chinese Universities

Cover and Content of Chemical Journal of Chinese Universities Vol.39 No.9(2018)

2018, 39(9): 0-0.

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Synthesis of Aluminophosphate Molecular Sieves by Ball Milling and Recrystallization^†

WANG Shuang,YU Yue,BAI Pu,LIU Jiancong,LI Lin,SONG Xiaowei

2018, 39(9): 1859-1866. doi:10.7503/cjcu20180114

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A rapid synthetic strategy through ball milling and recrystallization was successfully developed. Aluminophosphate molecular sieve with AWO topology was prepared by the precursor of two-dimensional(2D) layered aluminophosphate AlPO-IM. Simultaneously, metal-containing aluminophosphate molecular sieves with LAU topology were synthesized by introducing the metal heteroatoms in the ball-milling process. The phase transformation mechanism was comprehensively analyzed by Raman spectroscopy and CShM calculation. The results show that metal heteroatoms have an inorganic structure-directing effect in the synthesis of LAU molecular sieves. The ball milling-recrystallization method not only greatly shortens the crystallization time, but also converts the 2D layered aluminophosphates into a 3D molecular sieve under solvent-free conditions. Compared with the traditional hydrothermal/solvothermal synthesis, the ball milling-recrystallization method has the characteristics of high efficiency and energy saving, which expands the synthetic route of aluminophosphate molecular sieves.

Significant Improvement of CO Sensing Performance Based on Au-sensitized Double-shelled SnO₂ Hollow Nanocubes^†

MA Junfeng,ZENG Yi

2018, 39(9): 1867-1874. doi:10.7503/cjcu20180487

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Based on the unique structural merits of hollow interior, hierarchical nanoparticle-assembled and permeable double shells, the CO sensing performance of double-shelled SnO₂ nanocubes can be further promoted by the sensitization of the loaded Au nanoparticles. The crystallinity, morphology and structure of pure and Au-loaded SnO₂ hollow nanocubes(HNCs) are detailedly characterized and the results certify that the less-agglomerated configuration of Au-loaded SnO₂ is still reserved. Furthermore, the CO sensing performances of pure and Au-loaded SnO₂ HNCs demonstrate that Au-loaded SnO₂ exhibits a high response value of 20.9 to 24.7 mg/m³(20 ppm) CO at the optimal working temperature of 220 ℃, which is significantly higher than that of pure SnO₂. Besides their structural merits, the significant improvement of CO sensing properties can be attributed to the sensitized promotion of noble Au.

Preparation and Surface-enhanced Raman Scattering(SERS) of Single Au Nanodot^†

FENG Wei,WANG Bowei,ZHENG Yan,JIANG Yang

2018, 39(9): 1875-1880. doi:10.7503/cjcu20180467

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A novel and simple approach that combines both the character of laser beam and the size of the sphere array template was designed and the SERS study was carried out on “single” Au nanodot. The Au nanodots were deposited on the polystyrene sphere with a diameter of 2.6 μm. The nanodot has a diameter of ca. 300 nm which was characterized by means of atomic force microscope(AFM) and scanning electron microscope(SEM). The Raman enhancement factor for Au is on the order of 10⁶.

Synthesis of PEI-conjugated BaGdF₅ Nanoparticle for in vivo Dual-modal MR and CT Imaging^†

LIU Jianhua,SHI Zhan,LI Bo,ZHANG Tianqi,CUI Fengzhi,YUAN Qinghai

2018, 39(9): 1881-1885. doi:10.7503/cjcu20180357

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PEI-conjugated BaGdF₅ nanoparticles were synthesized via a one-pot facile but efficient microwave-assisted polyol process. Transmission electron microscopy(TEM), X-ray diffraction(XRD), FTIR spectroscopy, cytotoxicity test, CT imaging and MR imaging were used to characterize these well-prepared nanoparticles. TEM images indicated that these nanoparticles held an average diameter of 30 nm with uniform spherical character and relatively smooth surface. MTT result indicated these nanoparticles showed a very low cytotoxicity. Both in vitro and in vivo imaging results demonstrated that these nanoparticles exhibited excellent dual-modal MR and CT imaging capabilities, indicating their potential applications in further clinical areas.

Synthesis, Structure and Fluorescent Property of Indium-based Bimetallic Metal-organic Frameworks^†

WANG Dongmei,LIU Zihua,LI Guanghua,LIU Yunling,LI Chunxia

2018, 39(9): 1886-1892. doi:10.7503/cjcu20180269

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Two mixed-metal coordination polymers, [In(OH)Cu(TBA)₂(C₂H₆OH)]·NMF(1) and [In_0.5Cd_0.5(TBA)(CH₃OH)][NO₃]_0.5·2NMF(2)[H₂TBA=4-(1H-tetrazol-5-yl)-benzoic acid, NMF=N-methylformamide], were synthesized under solvothermal conditions and characterized by elemental analysis, powder X-ray diffraction(PXRD), thermogravimetric analysis(TGA) and single crystal X-ray diffraction. Complex 1 has a neutral 3D framework formed from the infinite chains and four-coordinated mononuclear Cu by TBA ligands. Compared to complex 1, In and Cd centers in complex 2 have the same infinite chains, which are bridged by TBA ligands to produce a cationic 3D structure. Complex 1 possesses a (4,4,8)-connected new topology while complex 2 belongs to (4,8)-connected topology. Notably, complex 2 can be used to detect Li⁺ and Fe³⁺ through either fluorescence enhancement or quenching effect, respectively. Thus complex 2 may be considered as a potential luminescent probe for the detection of Li⁺ and Fe³⁺.

Retention Behavior of Oligonucleotides under System Containing Mixed Ion-pair Reagents by IP-RPLC^†

QIAO Junqin,LIANG Chao,CAO Zhaoming,LIAN Hongzhen

2018, 39(9): 1893-1903. doi:10.7503/cjcu20180262

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The retention behaviors of oligonucleotides were investigated under mobile phase containing mixed ion-pair reagents of triethylamine/propylamine-acetate(TEA/PA-AA) and compared with that under classical mobile phase containing triethylamine acetate(TEAA) as ion-pair reagent by ion pair reversed-phase liquid chromatography(IP-RPLC). It is found that the retention of oligonucleotides under TEA/PA-AA system was always weaker than that under TEAA system when the concentration of ion-pair reagents was kept the same. In addition, retention time for most oligonucleotides became longer and longer as the increasing concentration of ion-pair reagents(20—120 mmol/L). As the special case, the retention time of (dC)_n(n>10) was relative stable. The reason should be that the retention of (dC)_n increases fast with the enhanced concentration of ion-pair reagents, and the maximum retention can be achieved under relative low concentration of ion-pair reagents. Additionally, short chain (dT)_n and hetero-oligonucleotides both had better resolution under TEA/PA-AA system than TEAA system. Nevertheless, (dA)_n and (dC)_n both had better resolution under TEAA system. What’s more, the dominated separation mechanism of oligonucleotides under the two systems both were ion-pair model, deduced from the relationship between retention factor k and ion-pair reagents concentration c_p. In general, TEA/PA-AA especially under moderate concentration is superior to TEAA in the separation of hetero-oligonucleotides having same chain length. Ion-pair reagent with low concentration improves the compa-tibility with electrospray ionization-mass spectrometry(ESI-MS), which benefits the qualitative analysis of oligonucleotides.

Quali-quantitative Profiling of Mucin-type O-Glycans in Normal and Tumor Cell Lines Based on Oligosaccharide Metabolic Engineering Combined with Mass Spectrometry^†

YANG Mingming,NAN Lijing,JIN Wanjun,WANG Chengjian,HUANG Linjuan,ZHANG Ying,WANG Zhongfu

2018, 39(9): 1904-1912. doi:10.7503/cjcu20180143

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The O-glycans on glycoproteins have important biological functions, and their abnormal expressions are closely related to the occurrence and development of several diseases such as tumor. Thus, it is of importance to conduct quali-quantitative profiling of O-glycans expression in normal and disease cells. However, due to the structural complexities and inhomogeneous expression of O-glycans, quali-quantitative analyses of these glycoconjugates still encounter challenges. In this study, based on the oligosaccharide metabolic engineering combined with mass spectrometry, we have profiled and analyzed O-glycans expressed in four tumor cell lines(HeLa, SMMC-7721, HepG2 and MCF-7) and one normal cell lines(L02) quali-quantitatively. The results showed that 19, 11, 6 and 5 O-glycans were observed in four cancer cell lines, HeLa, SMMC-7721, HepG2 and MCF-7 respectively. And 10 O-glycans were detected in one normal cell line(L02). Qualitative and relative quantitative comparison of O-glycans expressed in tumor and normal cell lines showed that three O-glycans(N1, H1N1A1 and H1N1A2) were observed in all cell lines. The number of O-glycans expressed in cancer cell lines is more than those in normal cells. Moreover, these O-glycans were highly fucosylated and sialylated. Further MS/MS data showed that these O-glycans were belonged to Core2 type Mucin O-glycans and their sugar compositions were H3N3F1A2, H4N4F1A2 and H5N5F1A1(fucosylated O-glycans) and H5N4A1, H4N4A2 and H5N5A2(sialylated O-glycans).

Microdroplet Detection of Protein Based on Superhydrophobic Polystyrene Film^†

XU Dan,DING Yadan,WANG Xue,CONG Tie,LIU Junping,HONG Xia,PAN Ying

2018, 39(9): 1913-1918. doi:10.7503/cjcu20180106

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Superhydrophobic polystyrene film with low water sliding angle was prepared by electrospinning, and the microdroplet detection technology of protein based on the superhydrophobic film was established. The superhydrophobic surface ensures the formation of spherical droplets, and the amount of sample required was thus decreased from hundreds of microliters to 10 μL. The low water sliding angle facilitates the manipulation of microdroplets and recycling of the detection substrates. Rapidly qualitative and sensitively quantitative detection of bovine serum albumin(BSA) molecules was achieved by the combination of biuret colorimetric assay and the microdroplet detection technology based on the superhydrophobic surface. Compared with the solution phase detection, the detection limit was decreased from 24.53 μmol/L to 1.490 μmol/L after drying the microdroplet on the electrospining polystyrene(PS) film due to the better concentration effect of the analytes on the superhydrophobic surface. This microdroplet detection technology of protein has a certain degree of universality. This study provides a new technical platform for the highly sensitive detection of trace biological/chemical molecules.

Structural Identification and Asymmetric-exchange Dynamics Study of Esomeprazole Magnesium in Specific Solution as Probed by Using ¹H NMR Spectra^†

WANG Ning,ZHU Huifang,WANG Lu,ZHANG Tiantian,GU Jiali,SHU Jie

2018, 39(9): 1919-1926. doi:10.7503/cjcu20180078

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EMD chloroform solution(1 mg/mL) was chosen as the research system. Based on the one-dimensional ¹H NMR spectrum, two-dimensional ¹H-¹H COSY spectrum, ¹H-¹H NOESY spectrum and ¹H-¹H ROESY spectrum, it is revealed that there are two tautomers coexisting in the EMD chloroform solution, named as A and B, with relative content of 64% and 36%. Furthermore, by analyzing the data of two-dimensional exchange spectra(2D EXSY) and temperature-dependent ¹H NMR spectra, the reaction rate constants k_AB and k_BA of A→B and B→A were deduced, which are 1.04 and 1.91 s^-1, respectively. Using these two sets of data, the equilibrium constant K_c of A→B was calculated, which are 0.56 and 0.54, respectively. The K_c value derived from the relative concentration is matched with the value deduced from the reaction rate constants, proving the accuracy of the test results.

Critical Factors Affecting Noncovalent Interaction Between Pentapeptides Explored by Electrospray Ionization Mass Spectrometry^†

WU Fangling,CHU Yanqiu,CHEN Xin,WEI Wanghui,DING Chuanfan

2018, 39(9): 1927-1933. doi:10.7503/cjcu20180075

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The noncovalent interactions between two of the four pentapeptides including His-Val-Phe-Arg-Lys(HK), Ile-Tys-Lys-Val-Glu(IE), Val-Glu-Gly-Ile-Tyr(VY) and(Ala-Thr-Leu-Leu-Ser)(AS) were investigated by electrospray ionization mass spectrometry. The mass spectra show the formation of 1-1 complex by two of the four pentapeptides. The competitive reaction shows mass spectrometric signal for the complex of AS with VY and the complex of IE with VY are more stronger when the four pentapeptides were mixed together. The binding affinities of the complexes were determined by collision induced dissociation(CID) through survival yield vs. collision energy curves. The collision energy(CE_50%) order is AS-AS(12.9 eV)~HK-VY(12.8 eV)?IE-IE(18.6 eV)~HK-IE(19.7 eV)~AS-VY(20.7 eV)~IE-VY(20.3 eV)?AS-IE(23.1 eV)~VY-VY(22.3 eV), indicating that the binding affinities of the complexes are apparently affected by side-chain group R of the amino acid residue composing of pentapetides, that is, the binding affinities of the complexes will be stronger with increasing the polarity and basicity of the side-chain R of amino-acid residue. The main driving force for the formation of the complexes should be ionic such as hydrogen-bonding, but not hydrophobic. The satistics of CE_50% for the complexes of amino acids which can composed of four pentapeptide samples were plotted, which further confirmed the conclusions based on CID.

Determination of Brominated Flame Retardants in Environmental Water by Microwave-assisted Ionic Liquid/ionic Liquid Dispersive Liquid-liquid Microextraction Coupled with DART-Orbitrap Mass Spectrometry^†

SU Rui,WANG Yihan,CHEN Changbao,SUN Xiuli,LIU Shuying,YANG Hongmei

2018, 39(9): 1934-1941. doi:10.7503/cjcu20180026

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A new method termed microwave-assisted ionic liquid/ionic liquid dispersive liquid-liquid microextraction coupled with DART-Orbitrap mass spectrometry(MA-IL/IL-DLLME) was developed for the determination of selected five brominated flame retardants(BFRs) in environmental water. Instead of using hazardous organic solvents, two kinds of ionic liquids(ILs), hydrophobic IL([C₆MIM][PF₆]) and hydrophilic IL([C₄MIM][BF₄]), were used as extraction solvent and dispersion agent, respectively, in this method. In the extraction procedure, BFRs were extracted entirely into the [C₆MIM][PF₆] from environmental water samples with the help of [C₄MIM][BF₄]. After extraction, IL phase containing analytes was analyzed by direct analysis in real time-mass spectrometry(DART-MS). Several experimental parameters that might affect the extraction efficiency were investigated and optimized. Under the optimized experimental conditions, low limits of detection(LODs, 0.212—1.82 μg/L) were obtained. The present method also provides good recoveries(80.7%—107%) and acceptable precision(RSDs<10.2%). In addition, the negative ionization characteristics of 5 different BFRs were investigated using DART-Orbitrap MS. The experimental results demonstrated that the developed method contains the advantages including easy-to-use, high speed and high sensitivity for the analysis of BFRs in environmental water samples, showing potential application in the environmental science and environment pollution protection.

Isolation, Identification and Antioxidant Activity of Lignans in Jasminum lanceolarium^†

WANG Yanbing,ZHANG Hui,YANG Junshan,CHEN Bingpeng,SUN Jiaming

2018, 39(9): 1942-1947. doi:10.7503/cjcu20180159

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Using silica and Sephadex LH-20 column chromatographies, seven lignans, Jasminlanoside A(1),(+)-cycloolivil(2), syringaresinol-4-O-β-D-glucopyranoside(3), (+)-cycloolivil-6-O-β-D-glucopyranoside(4), (+)-cycloolivil-4'-O-β-D-glucopyranoside(5), (-)-olivil-4″-O-β-D-glucopyranoside(6) and syringare-sinol-4,4'-O-bis-β-D-glucopyranoside(7) were isolated from the extracts of Jasminum lanceolarium. Compound 1 was first found and compounds 3—6 were isolated from the Jasminum genus for the first time. The structure of compound 1 was determined by various spectral techniques. Compounds 1, 2, 4 and 5 exhibited antioxidant activity in the 1,1-diphenyl-2-picrylhydrazyl(DPPH) assay, with the highest activity in compound 5[(0.148±0.005) μmol/L].

Activation of Esterification Activity of Rhizopus Chinensis Lipase in Organic Media by Surfactant^†

YANG Yihan,WANG Dong,ZHANG Zhang,XU Yan

2018, 39(9): 1948-1953. doi:10.7503/cjcu20180148

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Rhizopus chinensis lipase(RCL) was co-lyophilized with surfactants and/or inorganic salts to improve the esterification activity in organic solvent. Effects of type and concentration of surfactants and/or inorganic salts on esterification activity were investigated. The results demonstrate that n-dodecyl-β-D-maltoside(DDM) can enhance esterification activity of RCL effectively. The critical factor for activation of non-aqueous activity is molar ratio of DDM to RCL, rather than concentration of DDM. Esterification activity cannot be activated until the molar ratio is greater than 30, and then increase with the ratio. Furthermore, addition of appropriate inorganic salts in medium can strengthen the DDM-induced activation. The DDM-activated RCLs were used to catalyze the synthesis of ethyl hexanoate in organic media and ethyl oleate in solvent-free system. Higher reaction rate and conversion were obtained, which suggests the applicability of this method.

Hydrogen Bonding Study on Protic Ionic Liquids Composed of N-Alkyl Ethylenediaminum Cations with Trifluoroacetic Anion^†

XU Yu,HUA Er

2018, 39(9): 1954-1960. doi:10.7503/cjcu20180309

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All possible molecular structures of chelating mono-protic ionic liquids(PILs) composed of N-alkyl(hexyl, octyl and 2-ethylhexyl) ethylenediaminum cations with trifluoroacetic acid(TFA) anion that form [HHex][TFA], [HOct][TFA] and [HEtHex][TFA] were studied by the density functional theory(DFT) at M06-2X/6-311G(d,p) level. Hydrogen bond and stabilites of five possible structures S1—S5 were investigated. The obtained data show that the hydrogen atom has been transferred from N—H of [HAlkyl]⁺ to O of [TFA]^- in the ion pairs, and O—H…N hydrogen bond was formed. The obtained inter-molecular interaction energies(Δ $E int BSSE$ ) corrected by BSSE for all the structures are in the region of -449.91—-522.87 kJ/mol. The IR results show that N—H vibration spectra is disappeared. In the meantime, the stronger O—H vibration spectra was appeared in the region of 2200—2700 cm^-1since stronger O—H…N hydrogen bond was formed between [Alkyl] and [HTFA]. The natural bond orbital(NBO) and the atoms in molecules(AIM) analysis were applied to quantify the strength of hydrogen bond interactions and the effects of hydrogen bonding interactions on the stability of molecular configurations. NBO analysis shows that the stabilization energy mainly caused by the interaction between the lone pair electron LP(N) in the [HAlkyl] and the anti-bonding orbital σ^*(H—O) in the [TFA]-LP(N)→σ^*(H—O). The protonation site of [HAlkyl]⁺, and the effect of the alkyl chain length and side chain on the strength of the hydrogen bonding between [HAlkyl] and [TFA] were also discussed.

Reaction Mechanism of the Elimination of Peroxyl Radical by TEMPO^†

CHEN Junchao,YAO Yuan,ZHANG Hui

2018, 39(9): 1961-1967. doi:10.7503/cjcu20180244

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Density functional theory(DFT), Møller-Plesset(MP) and frontier molecular orbital methods were employed to investigate the fundamental reaction mechanism of the elimination of peroxyl radical by 2,2,6,6-tetramethylpiperidin-1-oxyl(TEMPO) with and without weak acid environment. The results showed that the calculated result from M06-2x method is in more agreement with the relative experimental results than that from B3LYP method, suggesting that the former is more suitable for the present system. With weak acid environment, the protonated TEMPO undergoes proton coupled electron transfer and electron transfer to eliminate peroxyl radical and get the regeneration. Without acid environment, the elimination of peroxyl radical by TEMPO consists of four steps, the formation of alkoxyamine, β-hydrogen atom transfer, the decomposition of carbon radical, and the regeneration of TEMPO. After the energy calculations, the activation free energy of the elimination of peroxyl radical by TEMPO with weak acid environment is calculated to be 35.6 kJ/mol, much lower than 96.8 kJ/mol without weak acid environment, showing that weak acid environment is more favorable for the reaction and this phenomenon has also been reasonably explained.

Kinetics and Abnormal Inhibition of THF on Ethylene Hydrate Formation from Ice Powder Based on Conversion Rate^†

SHI Weiguang,QING Hongxia,ZHANG Shangshang,LU Xiaoyi,WANG Xiaofeng,LI Benxian,XU Xiaohu,LIU Weiguo,WANG Jun,DONG Zhaohui

2018, 39(9): 1968-1975. doi:10.7503/cjcu20180234

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The conversion rate of ice powder(α), as a key parameter on evaluation of hydrate formation from ice-gas interface, was calculated by using compressibility non-ideal gas equation. And the Avrami equation and the Arrhenius equation were combined to investigate the kinetic information and influence rule of temperature, pressure, and tetrahydrofuran(THF) on the synthesis of ethylene hydrate from ice. As a result, there is no induction period during the formation of ethylene hydrate from ice. And the ethylene hydrate is rapidly nucleated on the ice surface and grows in the one-dimensional direction with the same rate. The activation energy(E_a) of ethylene hydrate from ice powder is 21.28 kJ/mol at 260.05—269.75 K, which is much lower than that in aqueous phase. The final α is 19.20% under the initial ethylene pressure of 4.90 MPa and 269.75 K. The α rises with the pressure from 1.98 MPa to 4.90 MPa and temperature from 250.46 K to 269.75 K. And THF can reduce α and conversion efficiency of α, which can identify that THF has abnormal inhibition on the formation of ethylene hydrate from ice by molecular size effect.

Structure Prediction and Photoelectron Spectroscopy Study of Rare Earth-doped Silicon-based Clusters of MS

i q 7

(M=Eu, Sm, Yb; q=0, -1)^†

JIANG Xianming,WANG Huaiqian,CAO Yu,SUN Zhihui,CAO Yufang,WU Weibin

2018, 39(9): 1976-1984. doi:10.7503/cjcu20180218

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The geometrical structures, relative stabilities, electronic properties and magnetism of anionic and neutral lanthanide metal-doped silicon clusters were systematically investigated by using the Saunders Kick global stochastic search technique combined with density functional theory(DFT) calculations at the PBEPBE/RE/SDD/Si/6-311+G(d) level of theory. The calculation results show that the ground state structure for anionic cluster is a 3D structure with the RE atom M sitting on top(or bottom) of the pentagonal bipyramid while adding another Si to the normal direction of it. The lowest energy structure of the neutral cluster is formed by substituting a Si atom on the equatorial surface of a distorted bicapped octahedral with an M atom. The SmS $i 7 -$ cluster has the highest binding energy and doping energy in the three rare earth doped clusters, indicating that SmS $i 7 -$ is the most stable cluster among them. When M atoms(M=Eu, Sm, Yb) were added into the Si₇ cluster, due to their unique atomic magnetism, the non-magnetic Si₇ cluster would be magnetized. In addition, the simulated photoelectron spectra(PES) of top-several isomers of each cluster were also presented, which could provide a theoretical basis for further experiments.

High Efficiency Synthesis of FeY Type Zeolite and Its Heterogeneous Fenton Catalytic Degradation^†

ZHANG Wu,JI Yanyan,PENG Han,DAI Shaoying,LIU Ying,ZHANG Jimei,WANG Dongmei

2018, 39(9): 1985-1992. doi:10.7503/cjcu20180178

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Iron containing zeolite with FAU structure was synthesized via the wet-gel crystallization method to improve the traditional hydrothermal synthesis of zeolites. X-ray diffraction(XRD), scanning electron microscopy(SEM), Ultraviolet-visible(UV-Vis) spectroscopy, inductively coapled plasma(ICP) elemental analysis and X-ray photoelectron spectrometry(XPS) spectroscopy were used to study the structure, morphology and composition of the zeolites, which was compared with those of samples prepared by traditional hydrothermal synthetic method and direct ion exchanging method. FeY zeolites were employed into heterogeneous catalytic system based on Fenton reaction, which had good catalytic degradation performance against methylene blue. The effects on the degradation rate were evaluated, including initial pH value of solution, initial concentration of H₂O₂, dosage of catalyst as well as different preparation methods. The optimum operation parameters for the Fenton oxidation were determined. Stabilities of the catalysts were also studied by successive recycling experiments.

Hydrogen Storage and Electrochemical Properties of the Mg-free A₂B₇-type La_1-_xY_xNi_3.25Mn_0.15Al_0.1 Alloys with Superlattice Structure^†

ZHAO Lei,LUO Yongchun,DENG Anqiang,JIANG Wanting

2018, 39(9): 1993-2002. doi:10.7503/cjcu20180169

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The new Mg-free A₂B₇-type La_1-_xY_xNi_3.25Mn_0.15Al_0.1(x=0—1.00) annealed alloys with superlattice structure were prepared by vacuum arc melting and heat treatment(950 ℃×10 h). The influences of Y element on the microstructure, hydrogen storage behavior and electrochemical performance of annealed alloys were investigated systematically. The results show that the main phase of all the annealed alloys is Ce₂Ni₇-type. With the increase of Y content, phase abundance of the Ce₂Ni₇-type phase increases firstly and then decreases, meanwhile the cell volumes decreases gradually. The x=0—0.25 alloys are easy to form hydrogen-induced amorphization(HIA), resulting in the disappearance of the plateau of pressure-composition-temperature(PCT) curves. When x≥0.50, the alloys can effectively avoid the HIA, the PCT curves obviously present an approximately single platform, the maximum hydrogen storage capacity and the plateau pressure of hydrogenation is in the range of 1.418%—1.48%(mass fraction) and 0.026—0.097 MPa, respectively. Therefore, the hydrogen storage performance has been greatly improved. The electrochemical measurement results show that the x=0.50—0.85 alloys exhibit the high discharge capacity of 350.4—381 mA·h/g and the cyclic stability of 52%—85% after 100 cycles, and the alloy with x=0.67—0.75 has good hydrogen storage and comprehensive electrochemical properties. The high rate discharge ability(HRD₉₀₀) of the alloys is 64.5%—85.7% and reaction kinetics of the electrode is mainly controlled by the diffusion rate of the hydrogen atom in body phase of the alloys.

Preparation and Growth of Interfacial Ultrasmall Water Droplets Between Alkanes and Hydrophobic Solid^†

WANG Yao,WANG Yunpeng,CAI Meirong,LI Huanrong,YANG Zhongqiang

2018, 39(9): 2003-2009. doi:10.7503/cjcu20180167

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In “water-oil-solid” multiphase system, linear alkanes in liquid form were chosen as oil phase, a spontaneous formation method was used to create interfacial ultrasmall water droplets, in order to investigate how the oil properties influence the interfacial ultrasmall water droplet growth and systematically characterize how the interfacial ultrasmall water droplets grow and change over time. First, the oil-solid interface between alkanes(heptane to hexadecane, in total ten linear alkanes) and hydrophobic glass was examined by optical microscope. It was found that water molecules above oil phase can diffuse through oil layer and adsorb to the underlying solid substrate, resulting in the formation of ultrasmall water droplets. However, by varying alkane carbon chain length, the growth of interfacial ultrasmall water droplets did not show obvious regular changes. The morphology, position and growth of interfacial ultrasmall water droplets were characterized by laser scanning confocal microscopy with high resolution. It was observed that the morphology of interfacial ultrasmall water droplets was spherical and localized at the oil-solid interface, the size of water droplets increased over time, and adjacent water droplets showed fusion phenomenon. When the thickness of water droplets and oil film was close, the water droplets disrupted the oil film and disappeared. Based on Imaris software, the total volume of interfacial ultrasmall water droplets was calculated, and the change of water volume over time was explored. It was found that the formation of interfacial ultrasmall water droplets can be divided into three stages: growth, stability and degradation. In this work, a new model was established by extending the oil phase selection range of the interfacial ultrasmall water droplets spontaneously formed in the “water-oil-solid” multiphase system, which provided a new method for the preparation of interfacial ultrasmall droplets and experimental basis for the study of micro-nano scale wetting theory.

Facile Synthesis of Scale-like CoMn₂O₄ Nanosheets on Reduced Graphene Oxide for Supercapacitors^†

LI Long,HU Hongli,DING Shujiang

2018, 39(9): 2010-2016. doi:10.7503/cjcu20180158

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Scale-like CoMn₂O₄ nanosheets anchoring on reduced graphene oxide(CoMn₂O₄/rGO) were fabricated via a facile co-precipitation and thermal process. The resulting product of CoMn₂O₄/rGO was characterized by field emission scanning electron microscopy(FESEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS). When evaluated its potential as electrode material in supercapacitors, CoMn₂O₄/rGO nanocomposites exhibit enhanced energy storage performance with high specific capacitance(1000.8 F/g at 2 A/g) and excellent cycle stability(93.6% capacitance retention after 1000 cycles).

Nonlinear Spectroscopy Analysis for Electrocatalytic Oxidation of Methanol on PtRu/C Surface^†

SHI Yue,MAO Qing,XIAO Cheng,JING Weiyun,ZHANG Xueyuan

2018, 39(9): 2017-2024. doi:10.7503/cjcu20180156

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A new generation of electrochemical spectroscopic analysis——total harmonic distortion(THD) spectrum was used to characterize the nonlinear characteristic frequency response of methanol electrocatalytic oxidation on PtRu/C surface. By comparing the experimental and numerical results of THD spectra of methanol oxidation on Ru catalysts with different contents, this work have qualitatively investigated the feasibility of THD spectrum in methanol electrocatalytic oxidation mechanism identification and electrode performance diagnosis. The experimental results show that in the range of 0.25—1 Hz frequency domain, THD increases with the decrease of Ru content, and decreases with the decrease of methanol concentration. Compared to EIS, THD has advantages over this failure diagnosis due to its opposite tendency of experimental results. The results of numerical simulation of THD spectrum show that according to whether electrode-potential-related step exist in the oxidation of CO_ads and different isothermal adsorption models, the mechanism of methanol oxidation based on Kauranen-Frumkin/Temkin mechanism can reproduce steady state, linear and nonlinear frequency response of methanol electrocatalytic oxidation with different Ru content on PtRu/C surface.

Study on Redox Mechanism of 2-Methyl-naphthoquinonein Dimethyl Sulfoxide and Acetonitrile^†

ZHU Yun,LI Dan,JIN Baokang

2018, 39(9): 2025-2030. doi:10.7503/cjcu20180132

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The electrochemical characteristics of 2-methyl-naphthoquinone(MQ) was investigated in dimethyl sulfoxide(DMSO) and acetonitrile by cyclic voltammetry(CV) and in-situ Fourier transform infrared(FTIR) spectroelectrochemistry. The electrochemical performance of MQ is distinct in different solvent when the scan range was from 0 V to -1.8 V. The results of cyclic voltabsorptometry(CVA), derivative cyclic voltabsorptometry(DCVA) and high-temperature CV indicated MQ is reduced to anionic radical MQ^·- firstly in DMSO, and then converted to dianion MQ^2- , which was two-step one-electron transfering process. Nevertheless, MQ in acetonitrile dimerization took place accompanied by electrochemical reduction, in which anionic radical MQ^·- and dianion MQ^2- formed the dimer and further ruduced at more negative potential.

Hierarchical Porous ZnO Nanomaterial Synthesized with Corn Straw as Biological Templates and Its Photocatalytic Performance^†

HUANG Yuting,YING Zuping,ZHENG Jixing,ZHUANG Sigeng,LIU Lu,FENG Wei

2018, 39(9): 2031-2038. doi:10.7503/cjcu20180110

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Hierarchical porous ZnO nanomaterial was prepared using corn straw as biological template via roasting process. The components and crystal characterization of the material were investigated via X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), nitrogen adsorption-desorption analysis and UV-Vis spectrophotometry. The results show that the ZnO material synthesized by template method is wurtzite type. And the crystal particle size is 46.2 nm, the specific area is 32.8 m²/g. Irradiated with Xenon lamp, the rate of decolorization of methylene blue of ZnO material prepared by template method reaches 98%, which is 1.3 times of that prepared without template(74%). Moreover, the influence of pollutant concentration and dosage of catalyst were also investiggted. And the results reveal that ZnO materials synthesized by template method own low grain size but high specific surface area, when 0.15 g catalyst was used to degrade 100 mL of 20 mg/L(MB) solution for five times, the degration rate remained at 95%.

Sodium Alginate Directed Synthesis of ZnFe₂O₄ with Micro-nano Structure and Its Performance in Lithium Ion Batteries^†

WANG Qiuxian,LI Kai,YANG Beining,YUE Hongyun,YANG Shuting

2018, 39(9): 2039-2045. doi:10.7503/cjcu20180051

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In the addition of Sodium alginate as a structure-directing agent, different micro-nano structures of anode materials ZnFe₂O₄/C were synthesized by the hydrothermal method. The structural and morphological properties were investigated by X-ray diffraction(XRD), field emission scanning electron microscopy(SEM), transmission electron microscopy(TEM) and Raman spectroscopy(Raman). The electrochemical performance was examined by galvanostatic charge-discharge test, cyclic voltammograms and electrochemical impedance spectroscopy. The results indicate that dandelion-liked ZnFe₂O₄/C has a reversible capacity of 2100 mA·h/g after 100 cycles at 1000 mA/g. In addition, the role of sodium alginate and the effect of different structures on electrical performance have also been investigated.

Cross-linking of Imidazole-grafted Sulfonated Poly(ether ether ketone) as Proton Exchange Membranes for Direct Methanol Fuel Cells^†

ZHU Xingye,QIAN Huidong,JIANG Jingjing,YUE Zhouying,XU Jianfeng,ZOU Zhiqing,YANG Hui

2018, 39(9): 2046-2053. doi:10.7503/cjcu20180084

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Sulfonated poly(ether ether ketone)(SPEEK) membrane is considered as a promising candidate to replace the Nafion membrane for the direct methanol fuel cell(DMFC) due to its high proton conductivity and excellent methanol resistance. However, the SPEEK always suffers the poor chemical stability. Herein, a novel imidazole functionalized cross-linked SPEEK membrane was synthesized via covalently cross-linked method. The results show that the modified SPEEK membrane exhibits greatly enhanced proton conductivity(0.14 S/cm at 25 ℃) in comparison with the Nafion 115 membrane(0.086 S/cm) by introducing the imidazole groups. Increasing the cross-linking degree of the membranes leads to a decrease in proton conductivity and a great reduction in methanol permeability due to the more compact network structure. When the cross-linking degree reaches 20%, the proton conductivity and methanol selectivity are 0.105 S/cm and 4.57×10⁵ S·s/cm³, respectively, demonstrating a good balance between proton conductor and methanol separator. Importantly, the oxidative and dimensional stabilities of cross-linked SPEEK membrane are significantly improved. A passive DMFC incorporated with the optimized Im-C-SPEEK-20 membrane delivers a peak power density of 29.7 mW/cm² at room temperature, close to that with Nafion 115(31.8 mW/cm²), suggesting a promising application potential in DMFCs.

Synthesis and Performance of Novel Bis-functional Cross-linked Anion Exchange Membranes^†

GUAN Mingming,CHEN Jia,TANG Shaokun

2018, 39(9): 2054-2061. doi:10.7503/cjcu20180049

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A polymerized ionic liquid copolymer composed of two ionic liquid precursors, 1-allyl-2-methylimidazole and 1-butyl-2-methylimidazole, and a poly(ionic liquid) main chain p(St-co-VBC) were synthesized via quaternization reaction to prepare anion exchange membranes(AEMs). The two ionic liquid precursors were synthesized from 2-methylimidazole. The poly(ionic liquid) main chain was prepared from styene(St) and p-chloromethylstyrene(VBC). The prepared membranes possessed crosslinked and comb shaped side-chain structure. Fourier transform infrared, scanning electron microscopy and thermogravimetry were used to investigate the molecule structure, morphology, hydroxide conductivity, thermal stability, alkaline stability and other properties of the membranes. The results showed that the AEMs had quite low water uptake, 36.7%—93.4%, and the ion exchange capacity was 1.61—2.16 mmol/g. The conductivity of p(St-co-VBC)-3 AEMs was as high as 68.4 mS/cm at 80 ℃. The AEMs displayed excellent alkaline stability and the hydroxide conductivity of p(St-co-VBC)-3 AEMs was still as high as 52.2 mS/cm after immersing in 1 mol/L NaOH solution for 240 h.

Preparation and Properties of Tetramethyl Ammonium Hydroxide Modified Polyvinylidene Fluoride with Styrene Sulfonated Membranes^†

LIU Qi,GUO Guibao,AN Shengli,LIU Jinyan

2018, 39(9): 2062-2070. doi:10.7503/cjcu20180042

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Poly(vinylidene fluoride)-graft-poly(styrene sulfonic acid)(PVDF-g-PSSA) membranes were synthesized via grafting styrene onto PVDF and then sulfonation. The PVDF of N-methylpyrrolidone solvent was initially modified by ammonium tetramethyl hydroxide(TMAH) methanol solution, and then the modified PVDF membrane was made after volatiling solvent. The styrene was grafted to the modified PVDF membrane, which utilized benzoyl peroxide(BPO) as the initiator. The microstructures, morphologies and sulfur distribution in the membranes were characterized by Fourier transform infrared spectroscope(FTIR), scanning electron microscopy(SEM), and energy-dispersive X-ray spectroscopy(EDX). Meanwhile, the effects of the TMAH mass fraction in methanol on proton conductivities and methanol permeabilities were investigated. The results indicated that PVDF was dehydrofluorinated by TMAH and carbon-carbon double bonds were obtained. The styrene was successfully grafted onto the modified PVDF membrane; the sulfur distribution in the interior and exterior of the membrane was homogeneous. The proton conductivities and methanol permeabilities of the PVDF-g-PSSA membranes increased with the increasing of TMAH mass fraction in methanol solution. When the TMAH mass fraction in methanol solution was 25%, the proton conductivity of the PVDF-g-PSSA membrane was 1.28×10^-2 S/cm and the methanol permeability was 4.58×10^-7 cm²/s, respectively. The membranes exhibited good thermal stability up to approximately 195 ℃. The peak power density of direct methanol fuel cell(DMFC) with above membrane was 16.45 mW/cm².

Synthesis and Characterization of Nanoparticles with Hydrogen Peroxide Sensitivity, Targeting and Fluorscence for Atherosclerosis

FANG Chao,ZHU Hanyu,LIU Ye,ZHAO Waiou,LI Yapeng,WANG Jingyuan

2018, 39(9): 2071-2079. doi:10.7503/cjcu20180033

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A multifunctional nanomicelle was designed for atherosclerosis theranostics, which was synthesized by decorating the poly(2-hydroxyethyl methacrylate)(PHEMA) with simvastatin(Sim) prodrug, fluorescent polyethylene glycol(FPEG) and the macrophages targeting molecules(ISO-1). The as-obtained polymer was confirmed by nuclear magnetic resonance(¹H NMR), Fourier transform infrared spectroscopy(FTIR) and gel permeation chromatography(GPC). The nanoparticle size and morphology were determined by dynamic light scattering(DLS) and transmission electron microscopy(TEM), which was spherical and with the size of about 100 nm. The MTT assay confirmed the biocompatibility of the nanomicelles. The targeting property was evaluated by cell uptake assay and observed via confocal laser scanning microscopy(CLSM). The results suggest that this multifunctional H₂O₂-respective targeting nanomicelles could become an effective tool for atherosclerosis therapy.

Characterization of High Polymerization Degree Ammonium Polyphosphate and Its Chain Structure by ³¹P NMR^†

LIU Yina,YANG Rongjie,LI Dinghua,LIANG Jiaxiang,HU Weiguo

2018, 39(9): 2080-2088. doi:10.7503/cjcu20180019

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Ammonium polyphosphate(APP) of high polymerization degree is an kind of important inorganic polymer flame retardant. Characterization of APP with high polymerization degree and its solution property are a meaningful topic. In this paper, quantitative liquid ³¹P nuclear magnetic resonance(NMR) is used to characterize APP polymerization degree and chain structures. A method of preparing aqueous APP solution by adding NaCl in water to auxiliary dissolving was established without resulting in APP degradation. The effects of different dissolution and testing temperature, and different NMR parameters were studied on the characterization of APP polymerization degree. Finally, The method to accurately characterize the APP polymerization degree was suggested based on liquid ³¹P NMR, that is: dissolving APP could be in water at 36 ℃ with auxi-liary NaCl salt, setting the temperature as 26 ℃ in ³¹P NMR testing. In this case, the good solubility of APP could be achieved, at same time no degradation of APP happened, the measurement of APP polymerization degree can be stable and accurate. The relaxation time(T₁) of terminal phosphorus(P_end) and middle phosphorus(P_mid) at different temperatures were determined by liquid ³¹P NMR, and the relationship between T₁ and temperature was found to be linear. The relaxation time parameter(D₁) in ³¹P NMR has a great effect on the characterization of APP polymerization degree, and the polymerization degree of APP will be inaccurate when the setting of D₁ could not meet the T₁ required for phosphorus. Characterization of APP chain structures by ³¹P NMR showed that there are three kinds of chemical environments in the terminal phosphorus of APP, that is the P connecting with two N $H 4 +$ , one N $H 4 +$ and one H⁺, and two H⁺, respectively. The NaCl concentration and testing temperature obviously influence the chemical shift of terminal phosphorus in the three chemical environments. It was verified that there was the middle phosphorus connecting with H⁺ in APP as well.

Improving Crystallization Behavior and Melt Strength of Poly(lactic acid) via Adding Talc and PLA-g-MAH^†

HAN Jiahui,HUANG Hanxiong,HUANG Yuxiao

2018, 39(9): 2089-2097. doi:10.7503/cjcu20180006

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Talc and PLA-g-maleic anhydride(PLA-g-MAH) were added to polylactide(PLA) to simultaneously improve its melt strength, crystallinity(X_c) and mechanical properties. Using a single-screw extruder with a chaotic mixing screw developed in our group, the PLA-g-MAH was prepared via reactive extrusion. Its grafting rate is measured to be 1%. Then, a series of PLA/talc(5%, 10% and 20%, mass fraction) and PLA/talc(20%, mass fraction)/PLA-g-MAH(5% and 10%, mass fraction) composites were prepared using the same extruder. The chaotic mixing in the extruder effectively improves the dispersion of the talc in the PLA matrix, and the talc of up to 20% almost does not agglomerate. Adding the PLA-g-MAH into the composites reduces the voids and the gaps around the talc on the cyrofractured surfaces and improves the interfacial adhesion between the PLA and talc. For the PLA/talc(20%) composite samples with 10% PLA-g-MAH, the α crystal content of the PLA is increased obviously and its X_c is increased to 31.6%. At 175 ℃, the melt strength for the PLA sample is relatively low(3.6 mN), and it is obviously enhanced(11.6 mN) for the composite sample with 20% talc. The explanation for this is as follows. The well dispersed talc has a reinforcing effect on the PLA melt and increases the crystallization behavior of PLA; moreover, the draw-down force can improve both effects of the orientation-induced PLA crystallization and the increased PLA crystallization behavior by the added talc. Compared with the PLA sample, the PLA/talc(20%)/PLA-g-MAH(5%) sample exhibits increments of 51.7% and 16.9% for the Young’s modulus and impact strength, respectively.

Preparation of Polyrotaxane Cross-linking Agent with “Pulley” Effect and Its Potential Application in Swelling Grain Used as Profile Control and Water Plugging Agent^†

TIAN Yao,ZHANG Chunquan,WANG Wenzhe,ZHOU Yingfang,LU Yitong,ZHANG Peng,JIA Zhenfu,ZHOU Chengyu,CHEN Shilan

2018, 39(9): 2098-2104. doi:10.7503/cjcu20170856

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A kind of polyrotaxane with polymerizable double bonds was designed and prepared through three step reactions. Because the α-cyclodextrin can slide freely on the chain of polyvinyl alcohol, this polyrotaxane can be considered as a cross-linking agent with “pulley” effect. The structure of polyrotaxane was characterized by Fourier transform infrared spectrophotometer(FTIR), 2D nuclear magnetic resonance(NMR), X-ray diffraction(XRD), and so on. The swelling grains were prepared by copolymerization of acrylamide with novel polyrotaxane cross-linking agent and ordinary cross-linking agent N,N'-methylenebisacrylamide individually. The swelling ability and deformability of swelling grains were also investigated. After swelling for 51 h, for swelling grain prepared by novel polyrotaxane cross-linker, the water absorption is 8.32. The swelling grain is not broken and can restore the original state after receiving and with drawing 294.3 N external force. But for swelling grain prepared by ordinary cross-linker, the water absorption is 6.75. The swelling grain is broken after receiving 112.4 N external force. The swelling ability and deformability of swelling grain prepared by the polyrotaxane cross-linking agent are better than those of grain prepared by the ordinary chemical cross-linking agent.

Synthesis, Characterization and Gas Adsorption Properties of Hypercrosslinked Polymers Based on Carbazoles Containing Aldehyde or Ketone Groups^†

ZHANG Rongrong,YUAN Guangming,LUO Weihua

2018, 39(9): 2105-2212. doi:10.7503/cjcu20170823

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Three novel carbazoles CM-2, CM-3 and CM-4 were designed and synthesized by ketone- or aldehyde-functionalization of carbazole. Then a series of hypercrosslinked porous polycarbazoles(HPP-2, HPP-3 and HPP-4) was prepared using CM-2, CM-3 and CM-4 as monomers under the catalysis of FeCl₃. The structures of the novel carbazoles and the hypercrosslinked porous polycarbazoles(HPPs) were characterized by nuclear magnetic resonance(¹H NMR, ¹³C NMR), magic angle spinning nuclear magnetic resonance(MAS NMR), infrared(IR) and mass spectrometry(MS). The thermal stability and the gas(nitrogen, carbon dioxide and methane) adsorption properties of the obtained HPPs were also investigated. The results show that the structures of the novel carbazoles and the polymers are consistent with the molecular design. Three kinds of HPPs begin to degrade around 400 ℃ and render a mass loss less than 25% at 800 ℃, denoting that these materials have a good thermal stability. HPP-2, HPP-3 and HPP-4 present BET specific surface areas of 330, 420 and 660 m²/g, with pore sizes mainly distributed at 0.98, 0.96 and 1.07 nm, respectively. The adsorption capacities of CO₂ on HPP-2, HPP-3 and HPP-4 are 6.90%, 8.30% and 9.80%, while those of CH₄ on HPP-2, HPP-3 and HPP-4 are 1.10%, 1.30% and 1.60%, respectively. The results show that the obtained polymers possess mainly micropores and present high adsorption capacity for CO₂ and CH₄. This work provides a new approach for the synthesis of hypercrosslinked porous polycarbazoles.

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